1. Technical Field
The present disclosure relates generally to the production of biofuels. More specifically, the disclosure relates to a high shear process for culturing algae.
2. Background of the Invention
Petroleum reserve depletion, economic, and environmental pressures have influenced and reduced the production and refining of petroleum derived liquid fuels. As a result, increasing interest and investment into renewable sources of liquid hydrocarbons has accelerated. However, dependency on crop-derived biofuels is limited by growing season, harvesting, and limited crop viability. Further, the reliance on food-crops for biofuels represents a supply-side strain on worldwide foodstuffs, from grains to livestock, food-crop implementation faces increased hurdles to economic, long-term, viability as a source for liquid fuel replacement.
Algae do not face the same hurdles to viability for biofuels applications as crops, as they may be cultured and harvested year-round on relatively small land areas. Further, many algae have been discovered to produce significant quantities of upgradeable hydrocarbons, such as lipids. However, as water-living, carbon-fixing organisms, the development and storage of these hydrocarbons is limited by the diffusion of carbonaceous gases, such as carbon dioxide, through water. Alternate growth media, gas bubblers, and fluid beds implemented currently have not resulted in increased hydrocarbon production, as the diffusion of gases through the algae media limits carbon available for fixation, growth, and storage.
During harvesting, the quantity of hydrocarbons available for refining does not reach the theoretical yield calculated for a given algae density. As the harvesting, lysing, and separation steps in conventional processes are slow, on the scale of seconds and minutes, the hydrocarbon/lipids exposed to free radicals, digestive enzymes, and other intracellular biological compounds rapidly degrade. Biological degradation represents an additional hurdle to efficient conversion of algal biomass to upgradeable hydrocarbons. As such, industrial scale algal bio fuels represent an equally inefficient resource.